In healthy subjects and in patients with mild to moderate gastro-oesophageal reflux disease, gastro-oesophageal reflux occurs mainly during transient lower oesophageal sphincter (LOS) relaxations.1-3 Transient LOS relaxations are a neural reflex, organised in the brain stem, with efferent and afferent pathways travelling in the vagus nerve.3 Distention of the proximal stomach is a major trigger for the reflex to occur, although stimulation of the pharynx or the larynx may also contribute.3 It is clear that the initiation of the reflex requires activation of gastric mechanoreceptors.

Because of their pivotal role in the occurrence of gastro-oesophageal reflux, the neurophysiology and pharmacology of transient LOS relaxations are topics of intense ongoing research. Atropine is one of the drugs that were recently shown to inhibit gastro-oesophageal reflux by inhibiting transient LOS relaxations.4 It is unclear if atropine is acting at the level of the stomach, by altering the mechanosensitivity of the proximal stomach, or at the level of the brain stem, by interfering with central integrative processing.

In this issue of Gut, Lidums and colleagues5 used a gastric barostat procedure to study the influence of atropine on proximal gastric tone and on the occurrence of transient LOS relaxations in healthy subjects (see page 30). Atropine caused prolonged relaxation of …